Owl Nebula (M97, NGC 3587)

The Owl Nebula (M97, NGC 3587) is a planetary nebula in the constellation Ursa Major. It was the third to be discovered,
by Pierre Méchain in 1781, and was named
by Lord Rosse in 1848. The Owl is one of the
more complex planetary nebulae known. Its appearance has been interpreted
as that of a cylindrical torus shell (or globe without poles), viewed obliquely,
so that the projected matter-poor ends of the cylinder correspond with the
Owl's eyes. This shell is enveloped by a fainter nebula of lower ionization.
The mass of the nebula has been estimated at 0.15 solar mass and that of
the magnitude 16 central star at 0.7 solar mass.